Ted Cruz led Lt. Gov. David Dewhurst by 9 points in a recent internal poll conducted for the former Texas solicitor general's campaign, a Cruz source has confirmed.

From the earliest days of the race to replace retiring Sen. Kay Bailey Hutchison (R), Dewhurst has been the frontrunner. But in this survey, 49 percent of respondents said they would vote for Cruz. Forty percent supported Dewhurst, and 11 percent were undecided.

Sixty percent of those surveyed viewed Cruz favorably, with 21 percent saying they had an unfavorable opinion of him. Dewhurst had an almost identical favorability rating, 59 percent, while 30 percent viewed him unfavorably.

Those within the Cruz camp contend that the jump in Cruz's polling and name identification is because of the politically engaged nature of the respondents who indicated their intention to vote in the July 31 runoff.

The task of determining a likely runoff voter is one of the most difficult aspects of this race because statewide runoff elections, especially at this point in the year, are rare. Therefore, any polling in this race is of limited value.